Tag: nature

What Bristol’s biodiversity duty report doesn’t tell you

By the end of March this year, every council in England had to publish a report on what it is doing for biodiversity. Councils that are also local planning authorities — Bristol among them — must go further, and give details of the biodiversity net gain resulting, or expected to result, from the biodiversity gain plans they have approved.

This is done through the submission of a Biodiversity Gain Plan (BGP).

Some time earlier this year, Bristol City Council published its Biodiversity Duty Report (the Report) covering the period from January 2020 to December 2025. It is a handsome document, and much of it is genuinely positive: it lists 43,523 trees planted, canopy cover up to 18.2%, and pesticide use down 42%. 

On the question of BNG, though, it publishes only a single table which can’t answer the question a local resident might ask: Is new development in Bristol leaving our local nature better off or worse off?

What BNG is meant to do

Since February 2024 most new developments in England have had to deliver a 10% increase in biodiversity. Developers measure what’s on a site before they build — using a government metric calculation which converts various habitat types into ‘biodiversity units’ —  and then show how they’ll deliver at least 10% more biodiversity than was there before they started.

They can do this in three ways: improve habitat on the site itself; pay for habitat to be created somewhere else; or — as a last resort — buy statutory credits from the Government. Before building can start, the Council must approve the developer’s gain plan showing how the minimum 10% BNG will be achieved.

Each gain plan is a precise record (backed by a metric calculation) of what a development will achieve. Bristol has approved a number of these so far but the Report tells you almost nothing about what’s in them.

What Bristol actually published

Here’s everything the Council’s published about its approved gain plans, as listed in the Report:

Table from Bristol City Council's Biodiversity Duty Report summarising its seven approved biodiversity gain plans. On-site only: 3 plans, 2.56 units post-intervention, average net gain 275 per cent. Off-site only: 1 plan, 2.09 units. Combination of on-site and off-site: 3 plans, 3.56 units. Credits: none. No baseline figure is given for any row.

Look at the column headed ‘No. of Units post-intervention’. These are the biodiversity units expected after a development is completed. There’s no column for the value of the habitats that were there before (called the baseline). Without a baseline, we can’t know what the net gain percentage is. In the row labelled ‘On-site BNG only’ there’s a reported 275% average % net gain but the other rows are left blank, so it appears not to be an average across the seven plans reported. Three small schemes with very little habitat to begin with can easily produce a number like this: if a site starts with almost nothing, almost any new habitat can produce a large percentage increase. Published on its own, without the baseline values that would put it in proportion, it reads as a triumph but is meaningless because it lacks essential information.

What the gain plans we’ve examined say

Bristol Tree Forum has been collecting biodiversity gain plans from councils across England — 301 of them so far, from 34 authorities. We’ve found 18 for Bristol, 16 of which record a figure for the change in area habitat units on the development site. Twelve of the 16 lose habitat on site. Added together, the 18 Bristol plans show a net loss of 10.9 area habitat units within the red lines of the sites themselves. The four that gain contribute 0.24 units between them. One scheme, at Broomhill Road, records the loss of every unit on the site — 100%.

To be fair to the Council, most of those plans were approved during 2026 and so fall outside the period the Biodiversity Duty Report covers. However, six of them are dated on or before 31 December 2025 and belong squarely inside it; all of these six lose habitat on site, by 4.68 units between them.

Now, an on-site loss is not by itself a breach of anything. That’s exactly what the off-site habitat unit purchase option is for: where a site cannot accommodate the lost habitat on site, the developer is allowed to buy habitat units elsewhere to meet the 10% plus obligation. Nine of Bristol’s 18 plans deliver through a combination of on-site and off-site compensation, and four go entirely off-site. So, on paper, the obligation is met.

But a resident reading the Council’s report would have no idea that any of this was happening. The published table doesn’t state what the baseline habitat was or distinguish between gains and losses. It doesn’t say where the off-site habitat is. And it doesn’t name a single application, so there is no way to look one up.

Where does Bristol’s biodiversity go?

The report does contain one sentence that deserves more attention than it’s had. There’s no registered biodiversity gain site anywhere within the Bristol boundary. The Council’s own candidate sites ‘remain unregistered while a viable solution to procuring a legal agreement is worked towards’, and are still at scoping stage. As far as we’re aware, no Biodiversity Gain Site has yet been registered for the city.

That means every off-site unit bought to offset a Bristol development creates habitat outside the city. Thirteen of our 18 plans use off-site delivery in whole or in part. The habitat lost is in Bristol; the habitat created to compensate for it is not. So far, that compensation amounts to 14.60 units allocated to sites outside the city — 14.55 area units, 0.01 hedgerow units and 0.04 watercourse units. To see them, open https://bgs.bristoltrees.space/bgs-bodies, select LPA Allocation Maps and click on City of Bristol LPA on the map.

Other councils can manage it

Publishing a schedule of all the approved BGP approvals is not difficult. Other authorities are already doing it. For example, Cotswold District Council has published an appendix listing all 24 of its approved gain plans — application reference, date, delivery route, and the units and percentage change for habitats, watercourses and hedgerows on each one. Bolton publishes the same for its four, including the name of the habitat bank each one bought into. 

County Durham has not published a schedule of all its approved applications, but it has published the full Government reporting tables, which show, without flinching, that on-site habitat units across its 16 approved plans fell by an average of 30.85%.

Durham’s report is uncomfortable reading for Durham, but it is for that reason worth something; a report that cannot embarrass its author is not really a report.

What we’d like to see

Bristol has met the letter of its duty but it could have gone further and produced a meaningful schedule that would have made sense to the ordinary reader and been used to help inform a proper debate about how the city is (or is not) benefiting from the BNG regime. On our analysis, it’s not.

Three changes would fix this, and none of them requires new data — the Council already holds all of it:

  1. Publish the baseline alongside the post-development figure, so a net change can be worked out.
  2. List the approved gain plans individually, with the application reference, so anyone can find the application and check it.
  3. Say where the off-site units are, and how many have left the city.

There’s some urgency to this. The reporting cycle is five years, by which time a new Local Plan will probably have been adopted. If we have the information now, this might be used in the development of any new Local Plan so that it provides a real benefit to Bristolians. Unless Bristol chooses to publish an update voluntarily, the next time it’s legally required to tell us anything about biodiversity net gain will be 2031 — by which point seven years of development will have been permitted, built and largely finished, on the strength of a table that serves no practical purpose.

Bristol City Council’s Biodiversity Duty Report 2020–2025 is published at bristol.gov.uk. The figures attributed to gain plans in this article are drawn from Bristol Tree Forum’s own collection of biodiversity gain plans obtained from planning registers and freedom of information requests, and are ours rather than the Council’s. We’d be glad to be corrected on any of them.

The cover image above is extracted from the Council’s Biodiversity Duty Report.

Ancient trees, missing data, and the fight over Bristol Airport’s planned expansion

So far, most of the public alarm about this expansion has centred on Felton Common, the well-loved local nature reserve on the other side of the runway, where the airport wants to plant 8.5-metre approach lights and fencing across protected grassland. Campaigners under the Save Felton Common banner have campaigned hard against that ‘land grab’, and rightly so. But the fierce fight over the Common has largely overshadowed a second, quieter yet important threat next door — the loss of irreplaceable habitat at Cook’s Farm, which has drawn far less attention. That is what our objection is chiefly concerned with.

Bristol Airport wants to grow. Its planning application (ref. 26/P/0686/OU2) seeks permission to expand from 12 million passengers a year to 15 million. To do this, the airport needs more land — including Cook’s Farm, some 24 hectares of long-established agricultural countryside where hedgerows have stood since at least the 1840s and where some trees have been growing for centuries. The airport now proposes to compulsorily purchase the site so it can carry out its plans.

However, it first needs to persuade the planners that its proposal is acceptable. We say it’s not, and we’ve lodged a detailed objection. It is a technical document, full of hectares and habitat codes, but underneath the detail is a simple story: irreplaceable habitat is at risk, the evidence supporting the plans doesn’t add up, and the law says that should matter.

Here is what our objection says, in plain terms.

The heart of it: three veteran trees

The most emotive part of the case concerns three veteran trees growing in an ancient hedgerow on the boundary of Cook’s Farm — two Ash and one Sycamore. The airport doesn’t propose to simply cut them down. Instead, it plans to translocate them: lift them with a giant tree spade and replant them on the northern edge of the development.

That might sound like a reasonable compromise, but our objections explain why it’s not in careful detail.

A veteran tree isn’t just an old tree, especially those in long-established hedgerows. It’s a whole ecosystem — cavities, rot, deadwood and fungal growth that specialist insects, fungi and other wildlife depend on and cannot find anywhere else. These features take centuries to form. You cannot manufacture them, and you cannot move them.

Worse, veteran trees are extremely unlikely to survive being moved. Their biology works against them. Over centuries they’ve spent their reserves coping with drought, storms, disease and damage, leaving little in the tank to survive the shock of relocation. Their roots are extensive but fragile, they depend on specialised underground fungal networks built up over generations, and much of their internal wood is effectively dead but structurally essential — it can’t be repaired if damaged. Successful relocation needs around two full growing seasons of careful root preparation beforehand. Crucially, the airport’s plan makes no proposal to reduce the trees’ roots at all. As our objection bluntly puts it: if the trees are translocated without root reduction, they will die.

Our conclusion is that, for the purposes of a planning decision, these three veteran trees should be treated as lost. The airport itself seems to half-accept this: it promises a ‘compensation’ package of ten new future veteran trees and the artificial ‘veteranisation’ of ten existing trees. But you can’t conjure a veteran tree on demand. Even with the right conditions, it takes two or three decades for a ‘veteranised’ tree to start resembling the real thing — and it will still lack the fungal decay that gives a true veteran its ecological value.

The evidence doesn’t add up

Beyond the trees themselves, we found that the environmental evidence supporting the application is riddled with inconsistencies. This means that the application can’t properly be decided as it stands.

The airport is required to demonstrate that it will deliver ‘Biodiversity Net Gain’ — a calculation meant to prove development leaves nature in a measurably better state (at least 10%) than it was before development. But our objection shows the numbers in the official metric calculation simply don’t match the airport’s own ecological survey. The two documents use different habitat categories, different reference codes, and don’t cross-reference each other. Some habitats that appear in the survey are missing from the metric altogether. Habitat parcels aren’t sized, and their locations aren’t shown on the map. In short, it’s impossible to reconcile the airport’s own datasets.

The tree surveys are a particular problem. Three surveys tucked into the appendices fail to meet BS5837:2012, the British Standard for trees in planning. Between them they’re missing the surveyors’ names and qualifications, survey dates, crown-spread data, branch heights and directions, life-expectancy estimates, soil assessments, and even the number of trees in some groups. One key survey dates from June 2024 and is now out of date. And when we asked for the tree schedule in a usable spreadsheet format so we could check it, our request was refused — leaving them, in their words, to analyse the data ‘as best we can’.

Even working with that inadequate evidence, their interim analysis is striking. Of roughly 1,618 individual trees on the site, some 367 — more than a fifth — are set to be removed, along with a share of the site’s hedgerows, which the airport’s own figures and the survey record in wildly different numbers (10 hedgerow parcels in one document, 71 in another).

Why this is a matter of law, not just sentiment

This is where our objection turns from ecology to policy — and it’s the part that could decide the outcome.

National planning rules are clear about irreplaceable habitats. Paragraph 193(c) of the National Planning Policy Framework says development that causes the loss or deterioration of irreplaceable habitats — and it names ancient and veteran trees specifically — ‘should be refused, unless there are wholly exceptional reasons and a suitable compensation strategy exists’.

We make two arguments about this test:

  • First, it’s a two-part test that has to be met in sequence: you need both wholly exceptional reasons and a suitable compensation strategy. A compensation package — however good, and here they say it isn’t good — cannot on its own make the reasons ‘wholly exceptional’. The decision in Juden v London Borough of Tower Hamlets [2021] EWHC 1368 (Admin) backs this interpretation.
  • Second, we argue that this scheme doesn’t clear the ‘wholly exceptional’ bar at all. The Framework’s own example of exceptional reasons is nationally significant infrastructure — the kind of once-in-a-generation project decided by government. This application, we say, is simply about increasing the capacity of an existing airport. That’s not the sort of wholly exceptional circumstance the rules have in mind.

Our objection also points to local policy. North Somerset Council’s own adopted Core Strategy (Policy CS4) requires it to protect, connect and enhance important habitats, ‘particularly designated sites, ancient woodlands and veteran trees’. The same protection is included in the Council’s emerging 2041 Local Plan. Approving the loss of these veteran trees would go against the Council’s own rules.

What it comes down to

Strip away the appendices and the acronyms, and our case is straightforward. The airport wants to expand on to land that includes centuries-old, irreplaceable habitat. Its plan to ‘move’ three veteran trees is, on the evidence, a plan to kill them slowly. The paperwork meant to justify all this is inconsistent, incomplete and in places non-compliant with the relevant standards. National and local planning policy both say irreplaceable habitat like this should be protected, not traded away for extra passenger numbers.

Our central demand is modest but firm: these problems need to be resolved before the application can properly be decided. For anyone who cares about Cook’s Farm, its ancient hedgerows and the veteran trees growing in them, that’s the line worth holding.

Here is our full response to the application:

BTF Consolidated Comments – 06 May 2026

The small-sites rule change that could quietly cost your neighbourhood its trees

From 6 August 2026, a change to the planning rules takes effect that most people will never hear about — but it could reshape the trees on our streets, in our gardens and on the small plots being built on all over the country.

Here is the short version.

What is changing

When land is developed, the law has, since 2024, usually required a small boost to nature — a “Biodiversity Net Gain” of at least 10%. In plain terms, a development is meant to leave nature a little better off than it found it.

From 6 August, the smallest sites — those of 0.2 hectares or less (about 2,000 square metres, roughly a third of a football pitch, or a small cluster of houses and their gardens) — no longer have to do this at all.

For hard-pressed small builders, that is a welcome simplification. But there is a catch for trees.

Why trees are caught in the middle

Under the old rules, removing even a single tree was usually enough to bring a small project into the nature-boost system — because of the way a tree’s protected “footprint” is measured. In practice, that meant a developer could not quietly fell a tree on a small plot without having to make good the loss.

The new rule swaps that “what is the impact?” test for a much simpler “how big is the site?” test. If the site is 0.2 hectares or smaller, the nature rules simply do not apply — however many trees are cleared.

What that means on the ground

On a site right at the new limit, the equivalent of up to 48 small trees — or around a dozen mature ones — could be removed with no requirement to replace or compensate for them under this system. And the trees most exposed are exactly the ones we tend to notice most: established trees on small urban and infill plots.

What still protects trees

It is not a free-for-all. Tree Preservation Orders, conservation-area rules and the special protections for ancient and veteran trees all still apply — they sit entirely outside this change. Some councils also have their own local tree policies: Bristol’s Tree Replacement Standard, for example, still requires replacement planting whatever the new exemption says.

The snag is that these local protections only exist where a council has actually put them in place — and not every council has.

Why it matters

The change is a sensible piece of red-tape reduction for small builders. But it is also, almost by accident, a real step back for the everyday trees that give our neighbourhoods shade, character and wildlife. From August, whether the trees near you are protected will depend less on national nature rules and more on whether your council has its own policies — and on whether a particular tree happens to be covered by an order.

If you value the trees around you, it is worth asking your local council what protections are in place.

We have set out the full detail — the mechanics, the legal position, and what to watch next — in an accompanying briefing note.

Read the full briefing note here.

The Local Nature Recovery Strategy and Bristol: a reassessment

In January 2025 we argued that the West of England Local Nature Recovery Strategy (LNRS) would do little to improve biodiversity net gain (BNG) in proposed development sites in Bristol. Since then, three things have changed enough to warrant a second look:

A follow-up to our January 2025 post, The Local Nature Recovery Strategy fails to deliver for Bristol.

  1. The emerging Bristol Local Plan has moved to the final stages of the public examination and the timetable for the 2045 Local Plan has been published.
  2. The West of England Mayoral Combined Authority (WECA) has published detailed guidance for developers and ecologists.
  3. We have been able to measure how much of the city the LNRS focus areas cover.

    These three changes mean that the picture is now more nuanced than a simple ‘fails to deliver’, but the practical conclusion is broadly the same. This post sets out why.

    What the latest LNRS has now made explicit

    WECA’s guide for planners, ecologists and developers, together with a dedicated BNG strategic-significance map, now spells out how the 15% Strategic Significance Multiplier uplift is meant to work. To attract the uplift, a proposed intervention must be in a mapped focus area for nature recovery and deliver a measure recommended (mapped) for that location.

    Two points in that guidance are worth dwelling on, because they confirm the argument we made in 2025 — this time in WECA’s own words.

    First, on baseline habitats. Our January post relied on Defra’s position that the multiplier applies only to habitats created or enhanced after development, not to what’s already on site – the baseline habitat. WECA’s FAQ now states this directly: the multiplier ‘is never applied to baseline habitats in the BNG Metric’. That is significant: it means the strategy can never reward the retention of existing habitat on a development site; but only new or enhanced habitats, and then only where a matching measure is mapped.

    Second, on where the mechanism is aimed. The single worked example in WECA’s guide is a developer purchasing off-site BNG units in a focus area. That’s a fair reflection of how the uplift is designed to behave: it’s a tool for steering off-site compensation and habitat banking towards priority locations, not something that typically assists the onsite footprint of a development itself.

    How much of Bristol is a focus area?

    In January we said it was ‘hard to imagine’ the LNRS helping on most Bristol sites, but we did not put a number on the coverage. We have now done so, using WECA’s own published data.

    Taking the Combined Authority’s mapped focus-area layer and clipping it to the official Bristol City Council boundary, 24.2% of the city — roughly 2,640 hectares of its 109 km² — lies within a focus area for nature recovery. (We checked the figure in two independent ways: a regular sampling grid and a random sample of over 90,000 points; both give 24.2%, and the method reproduces the city’s official area to within half a percent.)

    This is not a trivial share; anyone tempted to say the LNRS ‘barely touches’ Bristol should note that nearly a quarter of the city sits inside a focus area. But coverage is the wrong thing to count. That 24.2% is a ceiling — the maximum extent over which the multiplier could ever apply — before two much tighter filters are applied: the habitat being created or enhanced must match a measure mapped for that spot, and none of it can be baseline habitat.

    Coverage is not opportunity

    The more telling question is what is mapped, and where. When we count the individual measures that fall within the Bristol boundary, the focus areas turn out to be almost entirely watercourses and existing public green space that’s unlikely ever to be developed.

    LNRS measures mapped within the Bristol City boundary. Management/enhancement of existing habitat and watercourses (teal) dominates; new-habitat creation measures a developer could deliver on a site (amber) are comparatively few.

    River and floodplain measures dominate, followed by public parks & green space management and hedgerow, scrub and woodland under management. These are overwhelmingly measures for the management, restoration or enhancement of habitat that already exists — mostly along the Avon and Frome corridors, in the city’s parks, and on railway and river margins. This is land that is unlikely ever to be developed and, under the BNG regime, cannot be used to offset on-site habitat losses; BNG offsets may only be provided by registered Biodiversity Gain Sites (BGS). There are six in the LNRS but, currently, none are in Bristol.

    By contrast, the measures a developer might be able to deliver as new habitat on a site — creating woodland, hedgerows, wildflower meadow or mosaic habitat — appear only in the low tens of features and are themselves largely tied to the same green and blue corridors. So, the headline coverage figure and the practical opportunity point in opposite directions: a quarter of the city is mapped, yet the fraction of developable land where a scheme could both sit in a focus area and deliver a matching biodiversity improvement remains very small.

    The planning picture

    The wider planning position has moved on since January 2025, though not in a way that resolves the problem we identified at the time.

    Bristol’s emerging Local Plan completed its examination hearings last year with the final consultation has just completed. We are expecting the inspectors’ final report in the autumn so the plan is not yet adopted and still may not be. In the meantime, the Council having just published the timetable for the 2045 Local Plan which, when it starts this September, will not be completed until April 2029 at the earliest.

    Despite this, the two things we flagged in January still stand. No commitment has yet been made to designate any of Bristol’s focus-area sites — its parks, river corridors and green margins as BGSs available for off-site habitat mitigation — one route by which the uplift could be applied. Central Government has still not issued guidance on the role of the LNRS in planning decisions even though the Levelling-up and Regeneration Act requires plans to ‘take account’ of it. Until that guidance arrives, the strategy’s weight in day-to-day planning remains as defined under the BNG regime.

    Conclusion

    The LNRS is better documented than it was a year ago, and WECA deserves credit for setting out the mechanics clearly. On the specific question we raised in January 2025, that guidance has, if anything, confirmed our reading at the time: the multiplier cannot reward existing habitat. It is built for off-site delivery in priority locations rather than for the sites where most Bristol development happens. As none of these locations in the city are BGS sites, it is practically impossible to apply the 15% uplift they provide.

    The new coverage figure sharpens rather than softens the point. Yes, a quarter of the city is mapped as a focus area — but that land is the Avon, the Frome, in parks or railway land, all of which are already managed and enhanced in place. For a developer weighing up a site in Bristol, the chance that the strategy changes their BNG arithmetic is still low and, where it does, it will usually be through habitat bought outside the city.

    If the LNRS is to deliver the benefits promised for nature in Bristol, the gap is not in the mapping but in the mechanism: making suitable focus-area land available for off-site mitigation, and — as we suggested in January — allowing the city’s own adopted strategies, from its ecological network to its tree and green-space plans, to carry strategic significance where the LNRS does not.

    We suspect that this analysis is also likely to apply to other urban areas across England.

    Our earlier explanation of how strategic significance is assessed is set out in Assessing habitat parcels: strategic significance explained. Coverage and measure figures in this post were derived from the West of England Combined Authority’s LNRS layers on its Open Data Portal, clipped to the Bristol City Council boundary (ONS code E06000023), July 2026.

    Analytical research, policy review and initial drafting were undertaken with the assistance of Claude (Anthropic, 2025). All technical conclusions and professional judgements are those of the author.